1. Field of the Invention
This invention is related to an improved coupling mechanism for a radiographic source connector. More particularly, the coupling mechanism is directed to preventing inadvertent release of the connection.
2. Description of the Related Art
Radiographic systems are known for evaluating the condition of mechanical connections, e.g., welded connections in critical piping applications. In general, a radioactive source is located within the object to be evaluated at a point on the object where the evaluation is to be conducted. As an example, when the weld on a pipe is to be evaluated, a radioactive source is extended through the pipe to the weld under review, a photographic film or plate is provided adjacent to the weld such that the weld is between the plate and the radioactive source. The film is exposed for a predetermined amount of time and an image of the weld is thus created. The film is developed and the integrity of the weld is inspected.
Many systems are known for providing the radioactive source at the desired location. In general, a source wire is connected to a cable that is then extended through the conduit under examination. As shown in FIG. 1, a source assembly 10 includes a radioactive source capsule 12 at a distal end of a braided wire 16 with a connector assembly 14 coupled to a proximal end of the wire 16. The source assembly 10 is stored in a secure assembly to prevent inadvertent exposure of the user to radioactivity.
The source assembly 10 is retrieved from its housing by coupling a drive assembly 20, as shown in FIG. 2, to it. The drive assembly 20 includes a drive connector ball 22 attached to a drive wire 24 by a ball neck stem 25. The drive connector ball 22 couples to the connector assembly 14 and is then provided within the conduit being evaluated.
As shown in FIGS. 3A-3D, the connector assembly 14 includes a spring loaded up 30. The cup 30 is shaped to couple to the drive connector ball 22. A spring (not shown) within the connector assembly 14 urges the cup 30 toward a face F of the assembly 14. In the conventional system, the drive assembly 20 is able to move through approximately 90xc2x0 of rotation relative to a central axis xxe2x80x94x (FIG. 1), due to a slot that is provided in the face F of the connector assembly 14.
It is known, however, that the coupling of the drive connector ball 22 to the connector assembly 14 using the spring loaded cup 30 may be prone to inadvertent detachment. In other words, while the drive connector ball 22 can only be inserted into the connector assembly 14 by pulling the spring loaded cup 30 out of position, i.e., away from the face F, it is possible for the drive connector ball 22 to disengage without pulling the spring loaded cup 30 out of position. The drive connector ball 22 disengages because the ball neck 25 pushes against the spring loaded cup 30 as the drive assembly 20 moves through the 90xc2x0 of rotation. The ball neck 25 pushing against the spring loaded cup can occur when, for example, the radioactive source has been pushed outside of a conduit. In this situation, the radioactive source may be hanging down. When the source is retrieved it may catch an edge and become disengaged.
The inadvertent disconnecting of the source assembly 10 from the drive assembly 20 should be avoided at all costs. Such a disconnect means that the operator of the device has lost control over a radioactive source. In some instances, the source may be totally inaccessible and extreme measures would have to be taken to retrieve it. In other instances, the location of the radioactive source may not be discernable and therefore a dangerous condition exists in that a radioactive source is now lost and its whereabouts unknown.
Accordingly, a mechanism to reliably connect a radioactive source assembly to a drive assembly such that there is a 90xc2x0 range of motion between the two and where the two can only be disconnected by deliberate action on the part of the operator is necessary.
The present invention provides a coupling mechanism that reliably connects a source assembly to a drive assembly. A source connector includes a sleeve that also has a sleeve slot for providing additional coupling to a drive connector ball. The drive assembly can still be moved through a 90xc2x0 range of motion, however, it cannot be disconnected from the source assembly without overtly displacing the sleeve.
A coupling mechanism secures a source connector to a drive assembly to prevent unintentional release. The source connector includes a cup sleeve with a sleeve slot cut along its axis. The sleeve is spring-loaded to capture the ball end of a drive assembly by applying a positive locking force from the spring. The sleeve slot provides clearance for the neck of the ball end of the drive connector ball. This clearance allows the source connector to pivot approximately 90xc2x0 without detaching from the drive cable. The source connector cannot be disconnected from the drive assembly due to a force applied in any direction. The only mechanism for release is to intentionally move the sleeve in a direction opposite the urging of the spring and then remove the drive connector ball.